Switching system



A Y 1,611,252v P. M. SNAVELY SWITCHING SYSTEM v l Filed Jupe 25, 1922 fs sheets-'sheet s QV-ITE. |`mmf l] Y www , mi: F

Pau/ M Snam/y. l

Ptented Dec. .21', (1926;,

`PAUL M. sNAvELY, orisitooiiiriir,Y NEW YORK, AssreNonro AMERICAN `T'E'Lnrioi-vn .AND TELEGTNABH COMPANY, a CORPORATION or NEW YORK. f

' swrroHrNG SYSTEM.

kapplication meer June 23,

This invention relates to improvements inv switchingsystems and has particular reference to methods and means VforV controlling the signalsfor telephone transmission lines,

An object of theA invention is to control the connection of a subscribers line to a link circuit by a change in the condition'ot said circuit. Y

Another object is to Videntify one otra plurality of groups of subscribers lines and a line in said group by a changein the con'- dition of a link circuit serving said group.

Another object is to equally distribute-incomingcalls amongst a plurality ofoperators. positions, each of which has a signaling device common to a number of link V,circuits terminating thereat, by'signaling a different position each time a call is initiated.

The above and other objects will clearly appear from the "ollowingdetailed description when taken in connection with the acrompanying.drawin's wherein Figures lV to 3,- when arrangedrside by side as indicated Vb f* the lines extending to the maroins of the drawings, illustrate a preferred embodiment ot theinventive idea.. I

rIn carrying out the invention, the Asubscribers lines'are divided into groups, two' or' which are designated by the characters IA andB, there being only three ofthe lines lshown in group A and Atwo in group B.

Common to the various groups'ot lines are a plurality ot link circuits, two of which are shown at C and D whileothers are partially indicated at E and F (Fig. 3). lt will, ot course, be understood that as many of these `lin rsk may be provided as is necessary toV adequately liandlethe calls originating inthe various. groupsV ot1 subscribers lines. At

- theexchange where the link circuits terminate,.operators positions are provided, ,three of which are indicated at G, H and I in Fig. 3. .Each position has terminatingthereat a number ot link circuits tofwliich cord circuitssuchas'il, l' andl L are adapted to be connected in vorderpto extend the calls from the subscribers lines. Due to economy in sp'aoe,.iione'o;t the'link circuits for position l, which are sini-lar to the links at the other 'iositions,haveV been shown. The links associated with each position have a line sig- Y dialing device common thereto which is operate-l,-when a line isftaken for use,.to indicate Y to the operator uit 'the positionvr where.L theVV sig ' 'apparatus circuit.

'cuit and telephone headset. :that the invention will now be fully underal is operated tliata callis awaiting at-f 1922. V4serial No. 570,283;

tention'.v yThe invention contemplates VVthe equal distr-ibution of calls amongst thevari- Vousy operators, and to this endpineans'are proided, when one operator ,is busy v'respondingto a call, to operate the signaling device before the' next operat'ors position in i yexchange and the sequence ofv operation vthroughoutthe various positions will be repoated as other calls are initiated.`

lVhen an operator "receives an indicationv that a call ,is awaiting attention she connects one oi her Aavailable cord circuits to the jack of an idle link circuit appearing before` her rposition and then actuates her listening lrey I* i i to prepare ior the establislinientyot aconnection from her telephone head set to the calling line. the cord circuit ,into the :jack ot' a linlrcir- 'cuit initiates` the operation'foie line linding associated Vwith the seized.V link rlhis apparatus -is partly under VtheV control 'ot a mechanism M (Fig. 2) compris- The insertion of the plug of ing a number ot relays each orl which isindividual to a .group ,otlsubs'cribers lines.

llach line finding apparatus includes a number of multi-contact relays, certainot .which are assigned to theV several groups of lines. whileV others are individual to certain lines of'each group. In therdrawings (Fig. 1')

only three or" the, relays assigned to the groups and live of th'elnumber (say ten) `which would ordinarily-.be assignedfto the lines ofthe several groups arer shown'. Thus,

fwhen a linl is taken by an operatorone group and one line identifying relay is operated under the control of the relayv of the mechanism Mrcommon to the group of linesv .inwhicli the call has been initiated.V The closureot the contacts of the twooperated relaysthen connects the calling line'through the link circuit tov the operators cord cir- Y Itis believed,

hookat the' ksubscrihers fsubsta'tiomthe vline Ylos Y contacts of theV cut-oft1 relay 2. The closure ot the lett-hand contact ot relay 1 grounds the conductor 3 which is coininon to the subscribers lines in group A. This ground connection is non1 extended through the letthand winding of relay of the inechanisin M common to the lines ot group A, and troni thence to grounded battery through the `normalContact ot relay 5 which is common to the telephone lilies oft all ot the groups. Relay l encrgizes in this circuit and in closing its inner right-hand Contact establishes a locking circuit extending troni grounded battery through the winding ot relay 5, the right-hand normal contacts et relays, 7 and 8 of the inechanisiii M, the inner right-hand contact and right-hand wincing ci: relay l and from thence to ground at the lett-hand contact et relay 1. Assuming' that the operatorsk at the various positions G, H and l are idle and that no cord circuits are connected to the. various links appearing at said positions, the operation ot `relay 5 connects Vground through the right-hand `contactoit said relay, the nornial'contact ot' relay 9 individual to position Gr and troin thence to grounded battery through the signaling' device or lanip 10 which `is common to theA various link circuits such as C and D terminating at position GL rl`he operator at the latter position is notified by the lighting et the lainp 10 in the circuit described thereitor that Va call is awaitinv attention.

The operator at position Cr now inserts the plug 1101" a cord'circuit J into the jack 12 of an idle link C and then operates the listening key 13 ot the cord circuit to connect the tip and ringconductors thereof to her telephone head set indicated at CT. The closure ot the lowervcontact ot the key 13 connects batterjT tothe lett-hand windingV of relay 9 which thereupon operates to open at its norinalv contact the circuit for lanipl() which is then extinguished. The closure oi' the inner alternate contact ot relay 9 estab- "lisl'ies a vlocking circuit for said relay independent ot the low r contact 'ot the key 13.

said circuit being traceable 'troni grounti through the right-hand winding and inner alternate Contact of relay 9 and troni thence to battery through the contacter relay lllr which isconnion to the various operators7 positions. vrlhe closure ot' the outer alternate contact ot relay 9 switches the conducftor grounded' at the alternate contact ot' relay 5 through said contact ot relay 9 to the normal Contact ot relay 15 associated with position H. This action will not take place,

however, before the link circuit C has been Y connected to*V the calling subscribers line which results in therelease ot relay -5 as: will hereinafter-appear, since the. time interval betweenl theinsertien et the plug 11 into jack 12 yand the operation ot the key V13 is ordi-V f relay 26 individual Yto link C, said cirr vline 21, which circumstance niay oceir i previously described, Vthe lamp ldshculd ce'l nai-ily sutticient` to permit ofthe Vcomplete operation ot the line finding apparatus. Should the operator succeed in operating the key 13 before the calling line is connected to the link and relay 5 is released, the line signailing device or lainp 16 associated with the position H' will be momentarily lighted through the Yuorinal contact `of relay 15, but as soon as relay 5 releases lainp lwvill be extinguished: It the operator at position l-l should, in response to the lighting ot the lainp 16,insert the plug 17 ot the cord circuit L into Vjack 18 of anidlel link circuit such E, this operation will have no eii'ect upon the system and the operator at said position will be unsuccessful in establishing a connection to the calling subscribers line, as will later be described in detail.. When the operator at position C connects the cord circuit .l to

link C a circuit is established from grounded battery through supervisory lainp 19, sleeve Vcontacts of plug 11 and jack 12 andthe winding of relay 20 to ground. rl `he larip 19 Yis lightedin this circuit and remains in this condition until-the calling lineis connected to the link circuit bythe operation ofthe lainp 19 whereupon said lainp is extin-V 'giiishedv Thejextinguishnient ot this lamp then serves as an indication to the operator that she inay converse with the calling subscriber. Y Y I y' Relay 2O also operates inthe circuit above described and in closing its lett-hand contact, establishes va circuit for multi-contact it extending` troni grouiidedfbattery throigh Jthe winding ot relay 26, the' outer letthand contact ket relay 20, the righi'L-hand contact ot relay V27, the Contact or relay 28, the relay 41- and rr'oniA outer iight-hand Contact ot thence to ground through the inner letthand ncrinal contacts-ot relays 8,-? and (i i series. Relay 26 energises and establishes a locking circuit for itsel'ic extending troni grounded batteryzthrough its wl lowerinost Contact, ,the rlett-hand Contact ot Vrelay 27, the winding et relay 28Y anl troni thence to ground. over'the energizing circuit 'o'f relay 26. 'Relay 28 energizes in this circuit and in so doing oisconnects vthe lett-- hand contacts ot the sleeve relaysassociated with all or' the otherlink circuitst'roin the outer right-l contacts ot clays fl, G.' r" This disconnection p 'ents any i and 8. Y other relay siinilar to relay 26 of the othe link circuits tronioperating should an oper-v ator at one oit the other positions ineke a connection to one ot said link circuits before heilink circuit C is connected to the calling riding and luc losV y #1,611,252. e tis lighted Theloperation olf-relay `26A establishes a circuity for group identifying relay 29 of the'link circuit whichV relay is 4assrgned to'group A, said `circuit being traceable from Agrounded battery through the ywinding' of relay 29, conductor 30, the uppermost switching contact of relay 26,'the inner left-hand contact of relay. 4 and 'from thence to'ground at the lett-handnornialV contact or" relay 6 through the inner left-hand norinal contacts of relays 1 8 `and Si circuit ,is now'establishedl for relay 27 and` niultaneously with the closure of the circuit of relay 29 another. circuit is estabvlished for the `line identifying relay of thelink C assigned lto the line of each group, the units digit o'f which is 1.Y

This circuit is traceable troni grounded battery through the windingof relay 33, ,con-V f ductor 34,v lowerinost switching contact of f relay 26, the right-hand contact ofline relayl 1, thev outer left-hand` contact ofrelay 4 and the outer left-hand normalcontacts of relays 8, 7 Vand 6 to ground. vRelays 29 and l33 lock through their windings and respeetive lowerrnost switching contacts 35 and 36 and fromthence over the'coinrnon con-Y ductor 37 "to ground at the inner left hand contact 'of relay 20. The operation of relays 29and 33 results .in the connection of the tip, ring andY sleeve conductors olf, thetelephone line 21 through the uppermost sets' ofswitelii'irg contacts of relays; 29 -,and 33 lto the three yconductors or the link circuit C. A

cut-oif relay 2 of the line 21,l said circuit extending 4from y'grounded lbattery through the'r winding Vof relay27, the third froni thel uppermostjswitching contacts of relays 33- .upon releasing. The ropening of theiletthand contactof relay27 causes-thereleasc of relays 26 and 28,v the `latter of .wliichfin l closing its normal contact, Vnow permits .ot -theoperation of a relay suchfas relay 26 i Ai'issociated with some other link circuit when the flatter'is taken 4for use.` if, during the establisinent Vofthe connection of line 21 with the link cireuitC, another call should bev initiated infgroup A, the line relay individual to thejrcallingr line' .would be' operated to also ground the common Aconductor 3 so that when relay 1 is released,.-

' said conductor wouldi'eniain grounded and relays 4 and 5 would remain operated. The

cause the lighting of the lamp-'1 6 at position H through the outer alternate Contact ot.,

. relay 9 and the normal contact ofrelay 15;

Following the connection ofline .21to the circuit relay 28 wouldlrevleaseas pre-.-

Viously described regardless of:the'co'ntinu Lied connection' of ground to -the vccnductcr 3, In response to -theligliting of the'lainp 16,

the/operator at vposit-ion H iiiay now. conJ nect the 'plug y17 other cord circuit L vwith the jack 1 8 and theoperation of the line finding apparatusV associated with the link circuitE would then be effected inthe same manner as that described in connection "with the .link circuit C. The operator at position H, in' actuating thelistening key ot cord circuit L, causesy the energization and locking ori-clay 15 which thereupon switches the conductor grounded bythe operationl of vrelay 5i tothe normal contact of relay 38 located at the operators position l. In this inaiiner the next call incoming to the exj 'change would cause the lighting of the lainp 39 at position I so that said call would be ,handled by the operator at this position.

iiiter each one of the voperators has vanswered ya call andthe relay 38 has operated (assuming that this relay is associated with the Vlast Voperators position) a circuit is es r`tablished 'for 4.relay 14 extending troni grounded battery .through its. winding the "right-hand alternate contacts oi' relays 38, land 9 in series and the alternate Contact of relayf to ground, the latter relay being operated'in response tothe last call incoming to the;4 exchange which was taken care of by "thefoperator at position l. 'Relay 14 operates in the circuit described therefor andin lopening its contact disconnects battery from the lockingwindings. ot` relays .9, 15 and 38, whereuponv these Vrelays allrelease followed by the release of relay 14.', rEhe next call .received atl the exchange will now cause th'exlighting of Ylarnp A10 atv position G and vsucceeding calls will thereafter be distributedfto the other operators positions in the order of their appearance as has been previously described. Should anl operator leave herosition ineans are rovided for n l n n preventing the signaling device at lier posi.- tion. such as the .lain 10 Afrom lichting and f e s for passing an incoming call on to the next positionV injorder. This ineans lmay coin# prise av device, vsuch, as'the key 4Q which,

when operated, V-energi'zes relay 9 whicliv'reinains .energized unti'lrthe vkey is released.

The openingfothe.normal Contact of relll lay"9 prevents the lamp' 1()4 from heilig lighted and transfers the groundat relay 5 to the iiorina'l or outer alternate contact of i'e Vrlay l15. 1

'When the callqlia-s Jbeen tei'iifii-nated on lampz 19v to be ylighted as` a `signal tov ythe its ,right-hand Contact" and thus openrvthe tlieline 21 the supervisory relay; 24 of .the l"cord c-ircuit'is released, tlius causing the continued operation of the latter relay would Y operator that the link circuit 'C is no longer v Y locking circuits of relays 29. and 33. These Yrelays thereupon release to restore their witching contacts to normal and thus disconnect the line 2l from the link circuit C. Relays 2 and 27 then release and the apparatus is again in its normal condition.

What is claimed is:` v l. YIn artelephone system, subscribers lines, operators positions, link circuits for interconnecting said subscribers lines and said positions, cord circuits at said positions, and

switching means directly and jointly responsive toa connection between one of said cord circuits and one of said link circuits, and a .calling condition ont one ot said lines for connecting said calling line to said one of said link circuits..

2. ln a telephone system, subscribers lines, operators positions, link circuits for interconnecting` said subscribers lines and said.

Y positions, cord circuits at said posit-ions, and

' ot" said link circuits,

a line iinder directly and jointly responsive to a connection between one of said cord circuits and one of said link circuits, and a calling condition on Vone of said Ylines for connecting said calling line to jsaid one oii Vsaid link circuits.A

3. ln a telephone system, subscribers lines, operators positions, link circuits for interc'onnecting'said subscribers lines and said positions, cord circuits at said positions and a relay line finder directly 'and jointly responsive to a connection between one of said Vcord circuits and one roit-said link circuits,

and a calling condition on one ofsaid linesV .for connecting Vsaid calling line to said one il. ln a signaling system, scribers lines, operators positions,A a plurality oiI link circuits commo-n to said groups -oi lines, a plurality of cord circuits, means said lines and said positions, and switching devices.v certain Vof which. are individual to diiierent groups of lines andY others to lines ineach4 group, operable in response to a connection to one oil said link circuits for connecting a subscribers line to an operators position through said link circuit.

,6. ln a signaling system,groups ,oi' r subscribers" lines, operators positions, a plurality oitl link circuits'lfor Vinterconnecting said lines and said positions,.and switching devices, certain of which are individual to different groups of lines and Yothers to lines 'in each group, voperable in response to a connection to one vof said link circuits by groups of sub.- l

an operator for connecting one of said lines to an operators positiony throughV said link circuit.

V7. In a signaling system, groups of subscribers lines, operators positions, a plurality of link circuits for interconnecting said lines and said positions, switching devices, certain of whichV are individual to different groupsv of lines and others to lines in each group, operable in response to a connectionVK to one of said link circuits for connecting a subscribers line `to anropeiators position through said link circuit and means common to said group of lines for controlling said switching devices. Y

8. ln a signaling system, Vgroups of subscribers lines, operators positions, a plurality of link circuits for interconnecting said lines and. said positions, switching devices, r

certain of which are individual to diiierent groups of lines and others to lines in each group, operable in response to va connection in oneV of said link circuits forl connecting a subscribers line to anoperators'position through said link circuit and a plurality of relays, each common to the lines of a group, for controlling said switching devices.

9. In asignaling system, groups oi'subscribers lines, a line relay for each'line, operators posi-tions, a plurality of' link circuits or interconnecting said lines and said positions, Va mechanism. common to saidV groups oflines, switching devices associated Vwith eachv link circuit and responsive toa im I connection to anlink circuit vfor joining a jsubsciibers. line to said link circuit, certain oitl said switching devices being individual to groups of lines and controlled by said common mechanism and others of said switching devices beingindividual -to lines in each group and jointly controlled by said common mechanismVV and said line relays.

l0. In a signaling system, aplurality ot subscribers lines, a plurality of operators positions, agroup of link circuits terminatingat each of saidrpositions, a plurality of `cord circuitsV at each of said positions, a

signaling device at each position common to the group of link circuits terminating j' thereat` means' responsive toa call onV one of said lines for operating Vthe signaling devicey at only one oi said positions, means for connecting any of the said cord circuits to any .idle link circuit Vat said position, means responsive thereto for extending the said calling subscribers line' through the said idlel link circuit to the saidffcord circuit, and means for operating' the signaling devices at other operators positionsin rotation.

Vll. ln a signalingsystem, a plurality ot subscribers lines, plurality of operators positions, a groupof link circuits terminating at Veach orV said positions, a plurality -ot cord circi'iits at eacl-i Vor" said' positions, a

signaling device ateach position 'common to the group of link circuits terminating thereat, means responsive to a call on one olf said lines for operating the signaling device at only one of said positions, means for connecting any of the said oord circuits to.Vv

any idle link circuit at said position, means responsive thereto for extending the said calling subscribers line through the said idle link circuit to the said cord circuit, and means Jfor operating the signaling device l' at the next operators position in the order of its ,appearance When 'another call is initiated on vone of said'line s, Y Y 12.1111 a signaling system, a vplui'ality of subscribers lines, a plurality of operators.r

Y positions, a `group of link circuits terminating at each of said positions, a plurality ofV cord circuits'at .eaohfol said positions, a

signaling device at eacli position common to the group of link circuits terminating tliereat, means responsive to a call on one of'l said lines for operating the signaling device at only one'of said positions,'means for connecting any of the said cord circuits to any idle link circuit at saidgposition,

means responsive thereto for extending the another call onoiieof said lines/,fand means for preventing the operation ofthe signaling device at the iirst-iiamedV position until the signaling devices 'at all of the other positions have been operated.

13.7111y a signalingV system, a plurality of Y subscribersVV lines, anoperators position, a plurality of link circuits terminating .at

saidpositioman operators cord circuitpa signaling device associated therewith, means responsive'to the connection otsaid cord' circuit to one oi; said flinkl circuits or Joinling a subscribers line to said link circuit,

and ine-ans for disabling said vsignaling de- 45 vice Whensaid subscribers line is joined to said link oircuit. 1 y Y 14. Ina signalingv system, Va subscribers line,V an operators position', a link circuit f Y terminating thereat, a cord circuit, a'signal ing device, means Vresponsiveto a vconnection betvveensaidcord circuits andsaid link circuits at. said operators positionfor joining said subscribers line tosaid link cir- V cuit, and means for disabling said signaling device Whenfsaidl subscribes line is joined to said link circuit.V L r ln testiinonywhereof, l have signed my name tothis speciiication this 21st day or" June, 1922.; p i l i y i 5 PAUL M sNAvnLY, 

